Effects of Cannabis on the Adolescent Brain

Summary & key facts

This paper looked at brain scans, thinking tests, and lab studies to see how marijuana affects teenage brains. It found that teens who use marijuana a lot often do worse on thinking tests and show differences in brain structure and function. But researchers do not know if marijuana causes those differences or if some teens already have differences that make them more likely to use. The paper says we need studies that follow young people over time and that check how much they use and how cannabis and other drugs like alcohol interact.

Key facts:

• The authors reviewed three kinds of evidence: brain imaging, tests of thinking skills, and preclinical lab studies.
• Marijuana is the second most commonly used intoxicant during adolescence.
• Teens who use marijuana heavily often show worse performance on thinking and memory tests compared with teens who use less or not at all.
• Heavy teen marijuana use is often linked with changes in overall brain structure and in the tiny wiring of the brain.
• Studies also find altered brain functioning in heavy-using teens, meaning their brains work differently on scans during tasks.
• It is not yet clear whether these differences are caused by marijuana, or whether some teens already had differences that led them to use more.
• The authors recommend long-term studies that follow teens over time to separate dose-related effects from pre-existing differences and to study how cannabis and alcohol together affect brain development.

Abstract

This article reviews neuroimaging, neurocognitive, and preclinical findings on the effects of cannabis on the adolescent brain. Marijuana is the second most widely used intoxicant in adolescence, and teens who engage in heavy marijuana use often show disadvantages in neurocognitive performance, macrostructural and microstructural brain development, and alterations in brain functioning. It remains unclear whether such disadvantages reflect pre-existing differences that lead to increased substances use and further changes in brain architecture and behavioral outcomes. Future work should focus on prospective investigations to help disentangle dose-dependent effects from pre-existing effects, and to better understand the interactive relationships with other commonly abused substances (e.g., alcohol) to better understand the role of regular cannabis use on neurodevelopmental trajectories.

Topics

Cannabis and Cannabinoid Research Neuroscience and Neuropharmacology Research Prenatal Substance Exposure Effects

Categories

Health Sciences Medicine Pharmacology

Tags

Brain development Cannabidiol Cannabis Clinical psychology Cognition Developmental psychology Effects of cannabis Medicine Neurocognitive Neuroimaging Neuroscience Psychiatry Psychology

Substances

Cannabis

Conditions & symptoms

Addiction Substance abuse disorder Difficulty focusing